1. Field of the Invention
The present invention relates generally to a vacuum interrupter, and more specifically to a pair of electrodes of the magnetic arc driving type used for the vacuum interrupter.
2. Description of the Prior Art
In a vacuum interrupter, special structures have been devised for a pair of electrodes in order to improve the performance of current interruption. One of the examples of these structures is a pair of electrodes of the magnetic arc driving type.
In a vacuum interrupter provided with a pair of electrodes of the magnetic arc driving type within the vacuum vessel, each electrode is formed roughly in a disk shape having a circular recessed portion at the center of one surface thereof, a circular contact surface formed on the same surfce thereof concentric with the circular recessed portion, and a number of separate arc-driving members extending from the peripheral edges thereof to the center thereof in a straight line or a spiral form around the contact surface thereof.
In a pair of conventional electrodes of the magnetic arc driving type used with the vacuum interrupter, the arc-driving members are radially symmetrical with respect to the center of the electrode in order to effectively drive the arc, generated whenever the electrodes are closed or opened, outwardly, and two types of electrodes having two different shapes opposite to each other with respect to the cross section are used for the movable electrode and fixed electrode, independently.
Accordingly, in order to manufacture these electrodes of the magnetic arc driving type by using, for example, forging steps, two kinds of different metal forging dies must be prepared for the reason explained above, thus increasing the number of manufacturing steps and the manufacturing cost.
Further, in the vacuum interrupter, since two different material contacts are usually used in order to prevent fusion sticking between the fixed and movable contacts, it is necessary to prepare two kinds of contacts in addition to a pair of fixed and movable electrode rods and a pair of fixed and movable electrodes of the magnetic arc driving type, thus increasing the number of elements and thereby the manufacturing cost.
A more detailed description of the electrodes of magnetic arc driving type will be made with reference to the attached drawings under DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS.